Method for more rapidly producing aeroconcrete building elements

ABSTRACT

A METHOD FOR CONTINUOUSLY PRODUCING BUILDING ELEMENTS OF AEROCONCRETE, WHEREIN COMPONENTS OF A MULTI-PART FORM INCLUDE BOTTOM PORTIONS WHICH ARE RECIRCULATED TO A FILLING STATION AFTER SETTING OF THE ELEMENTS BEING PRODUCED WHILE FRAMES AND INSERTS OF THE MULTI-PART FOAMS ARE RECIRCULATED AFTER STABILIZATION OF THE AEROCONCRETE WHICH HAS BEEN POURED, AND PRIOR TO THE USE ARE CLEANED AND GREASED. BY USING A MIXTURE OF ALUMINUM AND LIMESTONE POWDERS AS THE BLOWING AGENT AND BY PREHEATING THE COMCRETE MIXTURE TO ABOUT 20-35*C., THE AEROCONCRETE IS STABILIZED SUFFICIENTLY TO PERMIT REMOVAL OF THE DIE FRAMES WITHIN ABOUT 36 MINUTES AFTER POURING.   D R A W I N G

W. LANZ Aug. 17, 1971 METHOD FOR MORE RAPIDLY PRODUCING ABROCONCRBTEBUILDING ELEMENTS 5 Sheets-Shoat 1 Original Filed May 29, 1967 m m w."

or m r Z E T INVENTOR wallrer Lanz wee, 2-.

Aug. 17, 1971 W L METHOD FOR MORE RAPIDLY PRODUCING AI'IHOCONURETEBUILDING ELEMENTS 3 Shoots-Shoot (5 Original Filed May 29, 1967 l 6 \NFma 9 v mw J W V o b a kwzvm 35 LC... M rm 5 arlbu k F m 6/ u wa A; "I" lmm Cl INVENTOR WaHer Lanz United States Patent US. Cl. 26442 2 ClaimsABSTRACT OF THE DISCLOSURE A method for continuously producing buildingelements of aeroconcrete, wherein components of a multi-part forminclude bottom portions which are recirculated to a filling stationafter setting of the elements being produced while frames and inserts ofthe multi-part forms are recirculated after stabilization of theaeroconcrete which has been poured, and prior to the use are cleaned andgreased.

By using a mixture of aluminum and limestone powders as the blowingagent and by preheating the concrete mixture to about -35 (3., theaeroconcrete is stabilized sufiiciently to permit removal of the dieframes within about 36 minutes after pouring.

This application is a continuation of Ser. No. 642,038, filed May 29,1967 and now abandoned.

This invention relates to a method for mechanized production of buildingelements of aeroconcrete having hollow spaces, and a plant for carryingout this method.

It is known to produce building elements with high isolating values ofaeroconcrete for construction of monolithic walls. In this caseproduction is effected by means of relatively small dies with adecomposable die frame and core portions insertable into the die byhand. When producing several elements in one die several separatingwalls insertable into the die frame by hand and a core portionassociated with each element insertable by hand are provided. This priorprocedure is only suitable for producing relatively small quantities ofelements, whereby the required working time is relatively high. With theprior method an aeroconcrete mixture was used requiring about two hoursfor completely expanding and stabilizing. Finally the cores wereimmediately removed from the mixture in the prior method after completestabilisation, since later removal would be impossible without damagingthe elements. However, the decomposable die frame was only decomposedand removed after complete setting of the elements and then the elementswere lifted off the die bottom.

The described prior method and the device serving for carrying it outare badly suited for a mechanized production of elements and it is theaim of the present invention to provide the conditions for economicproduction of elements. A first solution resides in the idea that themost expensive and heaviest parts of the die, namely the die frame andthe die insert should be recovered at a stage as early as possible ofthe production of the elements and should be made available for anothercasting operation. For this purpose, the method according to thisinvention is characterized by providing a number of dies, repeatedlyassembling, filling and providing with core means and separating wallmeans individual dies in a filling station at one end of conveyor means,removing said core means, separating wall means and frame portion fromsaid bottom portion simultaneously or within short time intervals at theother end of said conveyor means after a transfer time corresponding tothe time required for stabilisation of the mixture, and reconveying saidcore means, separating wall means and frame portions through a cleaningplant and a greasing plant to the filling station, while the buildingelements remain on the said bottom portion until complete setting of themixture, whereafter the bottom portions are returned to the fillingstation. Consequently, the die frame and the cores or a single dieinsert comprising cores respectively are recovered practically at thesame time, this allowing not only reduction of the number of die framesbut also simplifies the retransport of the die frames and core insertsfrom the dismantling station to the casting and filling station.

It is another object of this invention to increase the producingcapacity of a plant of a determined size and with a determined number ofdies and with good mechanical and isolating properties by substantiallyreducing the time interval from the casting to the dismantlingoperation, this being achieved in accordance with this invention by theuse of a mixture comprising 32-39 weight percent cement, 39-32 weightpercent sand, 25-30 weight percent water and at least .5 weight percentexpanding agent, whereby the mixture has a temperature of 28-35 C. whenpoured into the die. The expanding agent specified in Swiss Patent No.360,332 and consisting of 1-2 parts by volume of aluminum powder and 1-2parts by volume of limestone powder may preferably be used. With such amixture sufiicient stabilization within 30 to 40 minutes may beobtained, whereafter the cores and the die frame may be removed andreturned. It is thus possible to obtain a. high productivity with arelatively small number of die frames and core inserts and with limitedsize of the plant but relatively high operating speed and shortoperating sequence respectively.

This invention also relates to a plant for carrying out the abovemethod, this plant comprising a production line having conveyor meansfor simultaneously transporting a number of dies from a filling stationto a dismantling station, a cutting device in said dismantling stationfor removal of portions of the stabilized mixture extending upwardlyfrom the die, a running period of said conveyor means from said fillingstation to said dismantling station adapted to the time intervalrequired for stabilization of the mixture, and by means in said fillingstation following each other in the running direction of the conveyormeans for positioning of the bottom portion of the die, for putting theframe portion of the die onto said bottom portion, for stirring andpouring said mixture and for inserting said core means and separatingwall means. The filling station comprises the necessary equipment forassembling and filling the dies. This plant, specifically adapted to therequirements of the production of aeroconcrete preferably has a firstclosed circulation for the die frames and die inserts which areretransported from the dismantling station through a cleaning stationand a station for application of greasing mediums to the fillingstation, whereas in a second circulation the die bottoms with thedismantled elements are brought into a storing plant until the elementsare completely set, and are retransported from this storing plantthrough a cleaning and greasing plant to the filling station. Asubstantial advantage of the method and plant according to the invention:resides in the fact that only the simplest, lightest and cheapest partof the die, namely the die bottom, is required until the elements havecompletely set.

The invention will be explained below in detail with reference to theaccompanying drawing illustrating by way of example an embodiment of theplant according to the invention.

FIG. 1 is an elevation of the important part of the plant,

FIG. 2 is a top view of the part of the plant shown in FIG. 1,

FIG. 3 is a top View of a die,

FIG. 4 is an elevation of this die,

FIG. is a partial section of the die along line V-V in FIG. 3,

FIG. 6 is a partial section along line VIVI in FIG. 3, and

FIGS. 7-9 show details of a guiding device.

The plant illustrated in FIGS. 1 and 2 has a straight producing linealong which casting dies or molds may be transported from a fillingstation to a dismantling station. The filling station of the productionline has a fixed work table 1, along which the casting dies may beadvanced stepwise from the right to the left by means of a hydrauliccylinder 2 indicated in FIG. 2. In a first place A, the die bottoms 3schematically illustrated in FIGS. 1 and 2 as fiat sheets, are put ontothe table 1. Individual die bottoms put on the table are then shifted tothe left into position B by means of the advancing device 2, in which adie frame 5 is put onto the bottom from a return ramp 4 by means of asuitable hoist. In this way a die of parallelepipedic form open at theupper side is obtained into which a mixture may be poured. By the nextstepwise advancing movement, the bottom 3, provided with a die frame 5or the open die respectively, is shifted into a filling place C in whicha mixture described in detail later on is poured from a mixer 6 into theopen die. By the next advancing step, the filled die is brought into anoperating position D in which a schematically indicated core insert 8may be brought into the open die and into the mixture contained therein.The die provided with the die insert 8 moves from the table 1 onto theright-hand end of a conveyor line 9 during the next operating period.This conveyor line preferably consists of a suitable sliding Way alongwhich the bottoms 3 of the dies may slide, and of a conveyor chain 10having driving members, not shown, for driving one die each. The diesare continuously shifted without vibration to the left-hand end of thesliding way by the chain 10.

Water, sand and portland cement may be fed to the mixer 6 from threecontainers 11, 12 and 13 through suitable dosing devices not shown, andthrough a common collecting funnel, while the expanding agent such asequal parts of aluminum and limestone powders, is directly fed to themixer 6 from a small container 15.

At the outlet of the conveyor way 9, a table 16 extends transversely tothe direction of this conveyor way. By means of a device similar to thedevice 2, the dies arriving from the conveyor way on the table 16 may beshifted along this table into positions E and F. By means of a bracket17, a knife 18 in the form of a snowplow is supported above the table,the lower edge acting as a cutter being disposed at a distance above thetable 16 corresponding to the height of the die, such that the die maybe passed below the knife into position E practically without verticalclearance. Two stacking trucks 19 and 20 are disposed at the side of thetable 16, which are coupled with each other and may be displaced on atrack along the table 16. The stacking truck at the side of position Fserves for taking up the die bottoms carrying elements, while the diebottoms with elements stacked above each other on the other stackingtruck are simultaneously lifted out by means of a fork truck and may betransported into a warehouse, for example in which the elements arestored for setting.

Hoists 21 and 22 respectively, schematically illustrated in FIG. 1 only,are disposed above positions E and F, which serve for lifting the dieinsert and the die frame. respectively, from the die bottom and to lifethem onto the one of two conveyor bands 23 and 24 respectively. Theupper sides of both conveyor bands first pass through a cleaning device25 and into a device 26 for greasing the die frames and die inserts,respectively, with a suitable greasing agent. The cleaning device 25 mayinclude nozzles for cleaning the frames and die inserts by means ofvapour, compressed air, water, solvent agent or the like or acombination of several of these nozzles. The greasing device 26 includesa spraying device for spraying preferably a mixture of fat and oil ofsuch a consistency that fine vaporization and spraying and forming ofcontinuous well adhering layers is possible. From the greasing device26, the die inserts and die frames slide over the slide ways notdesignated to the places from where they are transferred onto the diebottom and into the already filled die respectively in the fillingstation.

In FIGS. 3 to 6 the particular die is illustrated. It consists, asmentioned above, of the fiat die bottom 3, the die frame 5 and the dieinsert 8.

The die frame has the form of a rectangular frame of sheets 29reinforced on the full circumference by U- profiles 30 welded to thesheets 29.

The die insert has a grid of separating walls 31 and 32 respectively ofsteel sheets welded to each other and disposed at right angles. Theseseparating walls 31 and 32 form a honeycombed grid so that with the dieinsert 8 put into the frame 5 elongated chambers 33 of rectangular crosssection are formed. Core portions made of welded sheets and centrallyextending through four chambers 33 are connected to the transverseseparating walls 31. As shown particularly in FIG. 6, the core portionssubstantially consist of a U-shaped bent metal-sheet canal 34 having twotransversely extending cuttings 35 in each chamber 33. Each cutting 35is closed by a V-shaped bent metal sheet 36 at its upper side and bymeans of metal sheets 37 at its faces, such metal sheets having aV-shaped cutting corresponding to the form of the metal sheet 36 attheir upper end. The ends of the core portions are closed by means ofend metal sheets 38. Finally, all core portions are closed at the upperside by means of a plane covering metal sheet 39.

As is seen from FIG. 6, the cores are somewhat wider at their upper sidethan at their lower side so that they may be lifted out of the mixturefilling the chamber 33 relatively easily. Thus, a core extends inlongitudinal direction through each chamber 33, hvaing an uppercontinuous horizontal prismatic portion of the sectional form seen inFIG. 6 and three vertical column-shaped portions separated from eachother by the cuttings 35. These cores correspond to the hollow spaces ofthe finished elements or stones which thus have two solid lateral wallportions interconnected by two transverse ribs corresponding to thecuttings 35.

Rings 40 are provided at four crossings of separating Walls 31 and 32respectively, at which the die insert may be lifted.

Production of hollow elements or stones of aeroconcrete by means of theillustrated plant explained above is as follows:

As already mentioned, the die bottoms 3 returning from the store,cleaned and greased at their upper surface are put into the fillingstation in position A, they are provided with a die frame in position Band filled in position C to a predetermined height with the previouslyprepared mixture. The mixer 6 is dimensioned for preparing quantitiessuitable for filling one die, and the required quantities of water,sand, portland cement and expanding agent are admitted from suitabledosing devices and mixed immediately after release of the previouslyprepared mixture. The die is filled in a well known manner to such aheight that at the end of its expansion the mixture slightly swells overthe die so that in any case the die is completely filled and the excessmaterial may be removed. When the die is still in position C, orimmediately after its arrival in position D, the mixture is againintensively stirred and distributed in the die so that all portions ofthe mixture, particularly constituents of different weight of the sandare uniformly distributed in the die. The die insert 8 is then insertedwhereafter the die arrives on the conveyor line 9.

During the continuous gradual displacement of the die along the slidingway 9, development of gas in the mixture begins, and the transfer timebetween the filling station and the dismantling station is so adjustedthat upon arrival of each form in the dismantling station, that is onthe table 16, the mixture has completely solidified and stabilized, butnot yet set or hardened. Each die shifted from the line 9 onto the table16 is pushed below the knife 18 into position E whereby mixture expandedabove the chambers 33 is sheared off evenly. The covering sheets 39promote clean cutting of the excess portions of the mixture in that theknife may slide on these sheets. In places where rings 40 are provided,the knife has openings through which the rings 40 may pass. When the sotreated die arrives in position E of the dismantling station, the dieinsert 8 is first lifted out and is put onto the conveyor band 23. Whenthe next die is shifted into position E, the die laying in this positionis pushed on into position F in which the frame is now lifted and putonto the conveyor band 24. After lifting out of the frame the die bottomtogether with the dismantled elements is shifted into the stacking,truck 19 placed in front of position F. While the stacking truck 19 isfilled, several die bottoms with dismantled elements are. simultaneouslyremoved from the stacking truck 20 by means of a fork lift truck notillustrated and are placed into the store for setting. When the stackingtruck 19 is filled, both stacking trucks are shifted upwardly in FIG. 2so that the stacking truck 20 unloaded in the meantime arrives again infront of position F and is gradually filled While the die bottoms withthe dismantled elements are removed from the stacking truck 19.

The die inserts and die frames are cleaned and greased in the mannerindicated above during their retransfer over the conveyor bands 23 and24 parallel to the producing line, and then return directly to thefilling station where they may be used again. The elements which wereproduced in the manner explained above are left in storage for about 2/2 days until the elements have completely set, whereafter the elementsare shifted off and stacked or transported away, While the remaining diebottoms are cleaned and greased and returned to the filling station.

It is obvious that for a determined expenditure, that is for adetermined size of the plant and for a determined number of availabledie frames and die inserts, the production capacity depends in the firstline from the time interval from the filling operation to dismantling.This time may be reduced to about 36 minutes when a mixture is usedcomprising 32-39, preferably 37.5 weight percent portland cement, 3932,preferably 37.5 weight percent sand, 2530, preferably 28.5 weightpercent water and at least .5 Weight percent expanding agent. Furthercare must be taken that during the casting operation, the mixture has arelatively high temperature of 20- C., this being achieved by placingthe plant in a room heated to at least 20 C. and preheating the Water to30- 32 C. The producing capacity is further determined by the sequence,that is, the time interval between each casting operation anddismantling operation respectively. Assuming that 20 dies are disposedbetween the filling station, and the dismantling station an interval of1.8 minutes is required, that is, each casting operation must becompleted within time intervals of 1.8 minutes. The duration of theoperating sequence is limited by the fact that the die insert must beput into the mixture poured into the die before development of gasbegins. With the mixture indicated above, gas development beginsrelatively soon and care must be taken that the die insert is insertednot later than 4 minutes after the end of the casting operation.

Careful greasing of the die portions in a suitable moment is ofsubstantial importance for the whole producing operation. Greasingshould be effected immediately before use of the die frames or dieinserts, if possible, so that the greasing device 26 should be locatedas near to the filling station as possible.

Various parts of the plant and operations may differ from thosedisclosed above for the illustrated embodiment.

While it is assumed for this embodiment that the mixture is stilldistributed and stirred by hand in position C or immediately prior toinsertion of the die insert in position D, another position may be addedbetween positions C and D in a filling station of correspondinglyincreased length, in which the filled mixture may be stirred. In thiscase a mechanical stirring device, having by way of example a number ofrelatively small stirring propellers with vertical shafts or having areciprocating stirring rake may be provided, which may be lowered intothe die frame without, however, touching the bottom and damaging thelayer of grease on the same.

It is not indispensable to lift out the die insert and the die frame indifferent places and in two separate operations, and it might undercircumstances be an advantage to simultaneously lift out both parts withthe same hoist and to put them onto the two conveyor bands 23 and 24. Inorder to avoid any relative transversal displacement of these dieportions during removal thereof, means may be provided for rigidinterconnection of both die portions for lifting them. If occasionarises, the hoist, for instance a vertically guided hydraulic press, maybe provided with a coupling device allowing simultaneous rigid couplingwith both die portions 5 and 8 to be lifted, and to lift them in precisevertical direction. At the same time it may be necessary to hold thefreely accessible portions of the mixture in the chambers 33 by means ofa counter holder or a holding-down appliance adapted to be lowered ontothe said freely accessible portions of the mixture but exertingpractically no pressure onto such mixture portions, in order that noportions of the mixture may be pulled upwardly with the die frame or dieinsert. The holding-down appliance may be a part of the verticallyguided lifting appliance mentioned above for simultaneously lifting thedie frame and die insert.

As already mentioned, it is important that the die insert and die frameare lifted out from the unset and consequently easily deformable mixtureexactly vertically without lateral displacement. As shown in FIGS. 7 to9, outer orienting angles 50 are mounted on levers 51 swingable round ashaft 52 by means of a double-acting hydraulic cylinder 53. The levers 51 engage into and are axially guided in slit cuttings 54 of the table 16in position F in all corners of the die bottom 3. When the orientingangles 50 are in their upper operative position shown in FIGS. 8 and 9,they tightly enclose the corners of the die bottom and thus exactlydetermine the position of this bottom. Guiding angles 55 mounted insidethe orienting angles 50 in the upper part thereof, engage the corners ofthe reinforcements 30 of the die frame 5 and guide the same in verticaldirection when it is lifted off the die bottom. The legs of angles 50and 55 extending in the swinging direction have their ends bentoutwardly for properly engaging and orienting the die bottom andengaging the die frame when swung into operative position. As shown inFIGS. 7 and 8, the die bottoms have enlarged rim portions 56 buttingagainst each other so that gaps are formed between adjacent die bottomsallowing entrance of the angles 50. The angles 50* and 55 may be swungoutwardly into a substantially horizontal inoperative position below thetable 16 for allowing shifting of another die from position E intoposition F and for shifting a die bottom with dismantled elements fromposition F into the stacking truck.

Since no displacement of the die frame on the die bottom must occur whenapplying the guide angles 55, care must either be taken that the dieframes can only be placed onto the die bottoms in a predeterminedrelative position, or in position B of the filling station acorresponding orienting appliance should be provided in order that thedie frames are always positioned on the die bottoms in preciselyprescribed position.

For producing elements of various forms, it is only necessary to use dieinserts of different type. The die frame and the die bottom may thus beused for all kinds of elements.

What I claim is:

1. A method for mechanized production of building elements ofaeroconcrete having hollow spaces, which comprises the steps of:

feeding a succession of die bottom members along a given path,

placing die frames from a source thCI'COlf onto the successive bottommembers at a first station along said path to provide die bottom frameassemblies presenting open topped die cavities,

introducing a mixture of concrete and an expanding agent, said mixtureconsisting essentially of 3239 weight percent cement, 39-32 weightpercent sand, 25-30 weight percent water, and at least .5 weight percentexpanding agent consisting essentially of 1-2 parts by volume ofaluminum powder and 1-2 parts by volume of limestone powder with themixture having a temperature of 20-35 C. when poured into the diecavities, and inserting core means and separating wall means, from asource thereof, into the die cavities at a first region along said pathadjacent said first station within a time interval of not more than 4minutes after pouring the mixture,

removing the core means, separating wall means, and

the die frames from successive assemblies at a second region along saidpath remote from said first region, recycling the removed die frames,core means and separating wall means from said region toward said firststation and said first region for rapid reuse to form the respectivesources for said die frames, core means and separating wall means whiletransporting the die bottom members with building elements thereon to aremote region for setting of the concrete forming the building elements,cleaning and greasing the die frames, core means and separating wallmeans during recycling thereof, maintaining the feed of the filled dieassemblies such that the time interval between the introduction of themixture at said first region and removal of the die frames, core meansand separating means at said second region is about 36 minutes, removingthe building elements from the die bottoms after the concrete is set,and recycling the die bottoms from said remote region to the inlet ofsaid path for delayed reuse. 2. A method according to claim 1,characterized in that said expanding agent essentially consists of equalparts of aluminum powder and limestone powder.

References Cited UNITED STATES PATENTS 3,442,991 5/1969 Lanz 26442FOREIGN PATENTS 360,332 3/1962 Switzerland 264-42 DONALD J. ARNOLD,Primary Examiner J. H. MILLER, Assistant Examiner US. Cl. X.R. 264-87

